Novel Doped Tungstovanadate and Molybdovanadate with Bi-antimony-Capped Keggin Structure

Three novel V-centred Keggin-based compounds containing cap-shaped Sb atoms: (HDMF)(2)[(VO4)W5.65V7.74 Sb2.61O36.77]center dot 6H(2)O (1), [Co(phen)(3)](2)[(VO4)Mo9.58V2.42Sb2O36]center dot 6H(2)O (2) and [Ni(phen)(2)(H2O)](2)[(VO4)Mo8V4Sb2 O-36]center dot 2H(2)O (3) (DMF = dimethylformamide; phen = 1,10-phenanthroline) have been synthesized and characterized. X-ray diffraction analysis revealed that compound 1 consists of an unusually one-dimensional 12-tungstovanadate Keggin-based polymer, in which the reduced tungstovanadate Keggin species are stabilized by introducing capping {VO} and {Sb} groups and then linked into chains via V(Sb)-O-V(Sb) interactions. Both 2 and 3 are built from secondary metal-ligand groups (Co-phen for 2, Ni-phen for 3) and 12-molybdovanadate doped Keggin-type cores with two antimony atoms capping two opposite sites. The anion in 3 represents a bi-capped and bi-supported Keggin-type structure. The electrochemical properties of 2- and 3-modified carbon paste electrodes (2-CPE and 3-CPE) are also studied.